Porifera

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Porifera

Porifera (pronounced: /pɒˈrɪfərə/), commonly known as sponges, are a phylum of simple multicellular organisms that lack true tissues and organs. The term "Porifera" is derived from the Latin words "porus" meaning "pore" and "ferre" meaning "to bear", referring to the numerous pores found on the body of these organisms.

Classification

Porifera are classified into three main classes: Calcarea, Demospongiae, and Hexactinellida.

  • Calcarea (pronounced: /kælˈkɛəriə/) are small, marine sponges characterized by spicules made out of calcium carbonate.
  • Demospongiae (pronounced: /ˌdɛmoʊˈspɒndʒiː/) are the largest class of sponges, comprising about 90% of all known sponge species. They are predominantly marine but also include some freshwater species.
  • Hexactinellida (pronounced: /ˌhɛksæktɪˈnɛlɪdə/), also known as glass sponges, are deep-sea sponges known for their unique glass-like skeletal structure made of silica.

Anatomy

The basic body plan of a Porifera consists of a system of canals and chambers, through which water is drawn in through the pores (ostia), filtered for food particles, and expelled through a larger opening called the osculum. The inner surface is lined with flagellated cells called choanocytes, which create a water current and capture food particles.

Reproduction

Porifera reproduce both sexually and asexually. Asexual reproduction occurs through budding, fragmentation, or the production of gemmules. Sexual reproduction involves the production of eggs and sperm, which are often produced by the same individual (hermaphroditism).

Ecological Role

Porifera play a significant role in marine ecosystems. They filter large volumes of water, removing bacteria and organic matter, and contribute to nutrient cycling. Some species also provide habitat for a variety of marine organisms.

Related Terms

  • Spicule: A small, sharp-pointed structure typically made of silica or calcium carbonate, found in large numbers in the body of a sponge.
  • Osculum: The large opening in a sponge's body through which water is expelled.
  • Choanocyte: A type of cell found in sponges that has a flagellum surrounded by a collar, used to generate a water current and capture food particles.

External links

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